1. Field of the Invention
The present invention relates to a time signal repeater which relays a radio signal including a time code for a radio correction clock receiving a radio signal to correct its time and to a time correction system using the same.
2. Description of the Related Art
A radio correction clock receives, for example, a standard time radio signal of a long wave (for example, 40 kHz in Japan) transmitting a standard time and corrects the time based on the received radio signal to display the precise time.
This type of radio correction clock has built into it a receiving circuit receiving a standard time radio signal and a control circuit for driving a hand driving system based on the received signal to correct the time. In the radio correction clock, the positions of the hands are corrected to positions according to the time code of the received radio signal.
A radio correction clock exclusively receives the standard time radio signal. There are many cases where it is placed in a location which the radio signal can hardly reach, for example, is in an apartment building or basement, and cannot receive the signal.
In order to eliminate this restriction on the location where the radio correction clock is placed, it has been proposed to provide a time signal repeater for receiving the standard time radio signal and modulating the received time signal by a predetermined carrier and transmitting the modulated signal, and to have the radio correction clock receive the signal transmitted from the repeater to correct the time (see for example Japanese Unexamined Patent Publication (Kokai) No. 5-333170).
Summarizing the problem to be solved by the invention, the modulation frequency of the standard time radio signal differs by country.
For example, the modulation frequency is 40 kHz in Japan, 60 kHz in the U.S., and 77.5 kHz in Germany.
As opposed to this, in the time signal repeaters currently proposed, the resonance frequency of the receiving antenna portion is fixed, so it is possible to use the repeaters in only one country.
Further, it may be considered to change the reception frequency of the radio correction clock to the frequency of the time signal repeater. This change, however, would be complicated and would involve both hardware and software, therefore this is not practical in terms of cost etc.